Signal processing equipment

ABSTRACT

An apparatus is provided for expanding, decompressing and editing signals, and particularly a signal processing equipment for printing or displaying images. The apparatus includes compression device for image data, storing device for storing the compression data, decompression device, and editing device for editing, using only signals for editing, wherein the transfer of the data between the device is executed using the compression data.

BACKGROUND OF THE INVENTION

This invention is concerned with an apparatus for effecting compression,decompression and editing of signals, and it particularly relates to anapparatus for printing and displaying images.

In laser beam printers, for example, the transfer of recording paper andthe printing operation are executed at the same speed. Since data isoutput so as to match the picture signal sent from a host computer withthe printing speed of a printing device, a memory for storing image dataof at least one image is generally required. However, a memory having ahuge capacity becomes necessary in order to realize a high picturequality with high resolution and high gradation, color, etc.

An example of a printing apparatus having a reduced memory capacity inorder to eliminate the above problem is disclosed in a preprint of“Image compression encoding method optimized for a full-color printer”,Japan Hardcopy '94 Fall Meeting, The 74th Conference of Japan Hardcopyfor the Society of Electrophotography of Japan, Nobutaka Miyake, p.13-16 (Dec. 2, 1994). According to this paper, the memory capacity forstoring image data is reduced by using image compression encoding meanscombining discrete cosine transformation and quantization.

Further, as means for signal compression at a fixed compression rate,the LSI under the product name of FBTC (IMAGE DATA COMPRESSION &DECOMPRESSION LSI), having the type name of M65790FP, is described inthe Mitsubishi Electric Corporation's data sheet. This LSI realizes aconstant compression rate of 8/3 for black and white images so that thememory address at the time of the output of the compression data isconverted to realize a processing of rotation and synthesis.

However, there are the following problems in the apparatuses disclosedin the above-mentioned publications:

(1) Regarding the apparatus in which image data is processed by using acompression method combining the discrete cosine transformation andquantization, the quantity of compressed data, that is, the compressionrate changes in accordance with the patterns of the images. Therefore,the memory capacity must be designed, considering the worst compressionrate.

(2) It is necessary to store image data of at least one page and rewritethe stored data so as to input page description languages, such as PostScript, as a command from the external apparatus, and to form and editthe image data. Since the compression rate changes in accordance withthe pattern of the images, there is no regularity to the memoryaddresses at which the compression data is stored. Therefore, even ifthe image data to be rewritten is part of the image plane, all imageplanes must be decoded. Further, when the data of a part of the image isrewritten, the compression rate of the part changes and writing into thememory area can not be done.

(3) The picture quality degradation easily occurs due to compressionprocessing of the image data. The Mitsubishi LSI has only the functionof compressing and decompressing image data of every one image unit. Andthis device does not consider the editing function in order to rewritethe compression data stored. In addition, since the object of theMitsubishi LSI is to produce a black and white image, signal processingfor each color either must be executed in a time series, or several LSIsare necessary in order to carry out signal processing for the colorimage.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide signal processingequipment which can reduce the memory capacity to be stored for formingor editing image data, solving the problems of the prior art.

A first feature of the present invention, in order to achieve the aboveobject, is in the provision of signal processing equipment havingcompression means for converting signals into compression data on thebasis of a compression procedure; storing means for storing thecompression data; decompression means for restoring the compression datafrom the storing means in accordance with a decompression processing;and editing means for executing signal processing of the decompressionsignals; wherein the signals as the edit object are restored by usingthe decompression means from the storing means, and the processingresult by the edit means is stored in the storing means by using thecompression means.

Further, a second feature of the invention is in the provision of signalprocessing equipment having compression means for converting signalsinto compression data on the basis of a compression procedure; storingmeans for storing the compression data; decompression means forrestoring the compression data from the storing means on the basis of adecompression procedure; and edit means for executing processing of thesignals as the object stored in the storing means; wherein the signalsto be the edited object are read out from the storing means, and theprocessing result by the edit means is stored in the storing means.

In addition, a third feature of the invention is in the provision ofsignal processing equipment having compression means for convertingsignals into compression data in accordance with a compressionprocedure; storing means for storing the compression data; decompressionmeans for restoring the compression data from the storing means inaccordance with a decompression procedure; edit means for executingsignal processing of the decompressed signals; and a switch for changingthe destination of the output of the signals restored by thedecompression means; wherein the switch changes the destination of theoutputs by the editing or the output of the signals.

The capacity of the memory for storing the image data is reduced, and,at the same time, the data transfer rate between the elements is reducedso that the formation and editing of the image data can be executed at ahigh speed, and so advantages not available in the conventional signalprocessing equipment can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are block diagrams of examples of the most basicconstruction of the signal processing equipment of the presentinvention.

FIG. 2A and FIG. 2B are block diagrams of the signal processingequipment of the present invention. FIG. 2A shows editing using inputsignals and signals stored in the storing means, and FIG. 2B showsexecution of editing processing on the basis of an editing command.

FIG. 3A and FIG. 3B are block diagrams of the signal processingequipment of the present invention. FIG. 3A shows the construction ofthe apparatus for decompressing and transmitting the edited signals, andFIG. 3B shows the construction of the apparatus with the signalformation means for forming the compression data form.

FIG. 4A is a block diagram of the printer, and FIG. 4B and FIG. 4C areblock diagrams of examples of the printer controller.

FIG. 5A and FIG. 5B are diagrams which show the edit processing of imagedata. FIG. 5A shows rewriting of the image data, and FIG. 5B showsrewriting of the compression data.

FIG. 6A and FIG. 6B are diagrams which show the memory address of thecompression data. FIG. 6A shows the case of a fixed compression rate,and FIG. 6B shows the case of a variable compression rate.

FIGS. 7A to 7F are functional diagrams showing the signal processing ofthe printer controller. FIG. 7A shows the data input of the pixel orderand line order. FIG. 7B shows the data input of an image color-planeorder. FIG. 7C shows the signal output (the image color-plane order) toa laser beam printer. FIG. 7D shows edit processing (overwriting of theimage data). FIG. 7E shows edit processing (overwriting on the storedimage data). FIG. 7F shows the expansion function (reduction of thepicture quality degradation by memory duplication).

FIG. 8.is a timing chart of signal processing.

FIG. 9 is a block diagram of an example of the printer controller.

FIG. 10A, FIG. 10B and FIG. 10C are block diagrams showing threeconstitutional examples of the signal processing equipment fordisplaying color images, characters, graphs, etc. on a display unit.

FIG. 11A shows an example of the screen of a filing apparatus, and FIG.11B is a block diagram of an example of the filing apparatus.

FIG. 12A and FIG. 12B are block diagrams showing examples of a one chipLSI. FIG. 12A shows the case of making one chip of the processor and theone image plane memory, and FIG. 12B shows the case of making one chipof the memory and the compression decompression means.

FIG. 13 is a block diagram of an example of the construction of the gameinstrument and shows the storing means in detail.

FIG. 14A and FIG. 14B are block diagrams of examples of the basicconstruction of the image display unit of the game instrument.

FIG. 15A is a block diagram of an example of the program compressionequipment, and FIG. 15B is a block diagram of an example of the signalprocedure of the program compression equipment.

FIG. 16 is a block diagram of the multimedia apparatus.

FIG. 17 is a processing flow diagram of the method of compression of acolor image.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The most basic construction of examples of the signal processingequipment of the present invention is shown in FIGS. 1A to 1C, whereininput signals are converted into compression data by compression means102, the compression data is stored in storing means 103, anddecompression means 104 restores the compression data. And then, editmeans 105 carries out edit processing by means of signals stored in theform of compression data in storing means 103 and of input signalssupplied thereto. Here, there is the case that the input signals aresignals which have the same characteristics as the signals stored ascompression data or that the signals are a command representing the kindof signal processing for the signals stored as compression data. Forexample, the input signals are expressed by a combination of image dataand a writing command for the image data, and the operation forre-writing a part of the signals stored as compression data is executedby interpreting both signals by use of edit means 105.

In another example, edit means 105 executes the input signal processingfor effecting rotation, expansion, compression, etc., for the signalsstored as compression data, using input signals. In any case, edit means105 carries out the operation for correctly reading out signals as theedit object from the signals stored-as compression data.

In FIG. 1B, edit processing of the signals stored in the form ofcompression data in storing means 103 is carried out by using edit means105, without restoration of the signals by the decompression means 104.This edit means does edit processing of the compression data on thebasis of the signal processing of compression means 102. In the codingmethod using a fixed compression rate, for example, because theinformation relating to the data constitution and the data quantity ofthe compression data is already known, signals on the basis of the formof the compression data are generated on the basis of this information.The edit processing of the signals stored in the form of compressiondata in storing means 103 can be carried out in the form of compressiondata.

In FIG. 1C, the input signals are converted into compression data bycompression means 102, and the compression data is stored in storingmeans 103. Decompression means 104 restores the compression data. Andthen, switch 108 selects whether the restored signals are output (outputdirection) or are transmitted to edit means 105 (edit direction). Editmeans 105 carries out edit processing by using the signals and the inputsignal stored in the form of compression data in storing means 103. Aswas mentioned above, in the image data, for example, the edit meansexecutes a signal processing to effect overwrite, re-writing, rotationand expansion, etc. by using the input signals. At the time of thesignal output, it is not necessary to make the edit means 105 operatebecause the edit processing for the output signal is unnecessary. Switch108 outputs the signal in the output direction. The compression meansand the decompression means reduce redundant information on the basis ofthe characteristics of the signals, the purpose of using the signals,etc. With regard to the use purpose, there is the case where loss-lessoperation is required, and vice versa. Even if the use purpose is thesame, there is the case where the redundancy is different according tothe characteristics of the signal output unit. The present invention isnot limited to a compression means and a decompression means of anyspecific configuration.

When the signal procedure of a fixed compression rate is used, thesignals formed by the input means or by the formation means and thecompression data of the storing means are associated with each other inaccordance with specific rules on the basis of the signal processing fora fixed compression rate. In case of image data, for example, thelocation of the image and the memory address (storing means) can betransformed by simple operational expressions, a table, etc. on thebasis of the rules. From this feature, for executing rewriting of thesignals using the edit means, only the signals for rewriting are outputfrom the storing means and can be input into the edit means.

FIGS. 2A and 2B show examples of the apparatus that edits the signalsstored in the storing means in the case where the input signals arecommands based on the page description language. In FIG. 2A, in case ofa command that instructs the signal formation on the basis of the pagedescription language, the signals are generated by using signalformation means 101 based on the input signals. In FIG. 2B, in case of acommand that calls for signal transformation on the basis of pagedescription language, edit processing is executed by using both thesignals formed by using signal formation means 101 and the signals whichare stored in the form of compression data in storing means 103 and arerestored by using decompression means 104. In FIGS. 2A and 2B relate toan example corresponding to the apparatus construction of FIG. 1C. It isneedless to say that the apparatus construction of FIG. 1A or FIG. 1Bcan be used as well.

FIG. 3A shows an arrangement wherein an apparatus that actually usessignals restored by decompression means 104 is constituted by anapparatus having compression means 102, transmission means 106,receiving means 107 and network 109. Because the data transmission iscarried out using compression data, a shortening of the transmissiontime can be realized. There is also an effect of reducing the cost ofthe receiving apparatus, because storing means 103 is not necessary onthe receiver side. FIG. 3B shows an example wherein signal formationmeans 1 a generates signals of the compression data form. As wasexplained above, in the case of a coding method using a fixedcompression rate, because the information relating to the dataconstruction and the data quantity of the compression data is known inadvance, signals in a compression data form can be generated on thisbasis of the information. As a result, because signal processing toeffect data compression need not be done, effects such as shortening ofthe signal processing time can be realized.

In the above example, the coding method for compressing data with afixed compression rate can be used as a compression and decompressionmeans. In the case of color image signals, for example, in order torealize a fixed compression rate, it is possible to employ means fordividing an image into blocks constituted by several pixels and forconverting the signals in the blocks into selection signals representingcolor signals of two kinds or so and a difference (image-resolution)among the signals.

On the other hand, the compression method using a variable compressionrate can be used. But, in the case of a variable compression rate, it isnecessary to provide means for associating the memory address of theindex and the compression data representing the location of the image atthe time of the compression of the image data. Rewriting of the imagedata at a specific place is carried out by referring to the means forassociating and by restoration of the compression data in the storingmeans. As the data quantity changes, when the image data after rewritingis compressed, signals sometimes cannot be stored in the former place.Therefore, writing is done to the empty part of the storing means, andthe memory address is newly set to the means for associating. If thisprocedure is used, while the compression means using a variablecompression rate can be used, the storing means control method becomescomplicated. If attention is paid to the decline of the processingspeed, the above compression method can be used without problem.

Yet, as the compression method, a block approximation code (BlockTruncation Coding), Huffman code, Arithmetic Coding and LZ (Lempel,Ziv), LZW code which is its improved type, etc. can be used. The presentinvention is not limited to a specific compression method. While, as apretreatment of the compression, processing such as calculation of thefinite difference value, the orthogonal transformation, wavelettransformation, histogram detection, edge detection, the rangeseparation, the color transformation and the block approximation can beused, the present invention is not limited thereto.

As described above, the present invention realizes reduction of thecapacity of the storing means and high speed of signal processing byusing a compression means, a decompression means, storing means and anedit means. From the viewpoint of signal flow, the construction forprocessing and transmitting signals as compression data can be realized,except for the input and output of signals. Even in the case where thesignals must be processed in the form of the original data, only thesignals as the object of processing are handled as original data.Further, as the storing means 103, apparatuses such as semiconductormemories, flash type memories, a hard disc apparatus, optical magneticdiscs, etc. can be used.

An example of the present invention will be explained by using theapparatus described below.

(1) A Printer Controller

The printer controller inputs commands, such as the page descriptionlanguage from the host computer, and the image data formed and edited onthe basis of the commands are output to the printing means, called aprinter engine. There is also a construction by which the formation andediting of the image data are executed on the host computer side, andthen the image data is transmitted according to the scanning order ofthe printer engine. In this case, there is a problem that the datatransfer time becomes longer, but this example can be presumed as thehost computer performs the function of the printer controller.

Here, in the printer controller it is normally difficult to carry outformation and editing of the image data in synchronism with theoperation of the printer engine, from the viewpoint of the signalprocessing speed. Therefore, in general, means for storing the imagedata for at least one image plane is provided in the printer controller.Especially, in an apparatus that executes the printing of one imageplane at a constant speed, like a laser beam printer, delay of theformation and editing of the image data is not allowed, and therefore,it is desirable that all image data for one image plane is formed,edited and stored in advance.

Thus, among means for constituting the printer controller, the formationmeans, the edit means and the storing means for the image data have beenconsidered necessary. In addition, signal transformation means wasprovided in order to improve the picture quality. But, as theimprovement of picture quality reproduction ability in the printerengine increases, the printing image has changed from black and white tomulti-color and further to full-color, and so the pixel density becomeshigher. As a result, the capacity of the image data constituting oneimage plane has become remarkably large.

This has created the following problems in the printer controller.

(a) The memory cost portion of the apparatus cost increases.

(b) The amount of image data to be edited becomes huge, and so the timerequired for signal processing becomes longer.

(c) The time required for the data transfer among various meansincreases.

In order to solve the above problems, an example of the presentinvention will be explained. FIG. 4A shows the basic construction of theprinter. FIG. 4B shows an example of the construction of the printercontroller. FIG. 4C shows another example of the construction of theprinter controller.

Image data is formed and edited using CPU 201 or ASIC (ApplicationSpecific IC) 202, based on commands input using input/output means 205from the host computer. The image data is converted into compressiondata and is stored in memory 204. And then, in synchronism with thetiming of the printing means of the printer engine, a signal is outputin order. CPU 201 takes the program data from ROM (Read Only Memory)203, which stores the operating program. Signal processing of theformation, the editing, etc. of the image data is executed by usingeither CPU 201 or ASIC 202 or both. Memory 204 has sufficient memorycapacity that image data for at least one image plane can be stored ascompression data. This leads to execution of the formation or editing ofthe image data and to the matching of the data transfer rate and withthe printer engine.

FIGS. 5A an 5B illustrate explains the principle of the editing of theimage data, that is, the rewriting of data. As shown in FIG. 5A, if theimage data is taken as the image of a manuscript, the image data subjectto the rewriting object in a certain specific place is input andre-written for the data, and then the data is written in the formerplace. On the other hand, in case the compression data stored in thememory is taken, as shown in FIG. 5B, the memory address of thecompression data for rewriting must be clear. In addition, there-written compression data must be stored again in the memory.

As shown in FIG. 6A, if the compression method employs a fixedcompression rate, the compression data to be re-written is read out fromthe memory, as mentioned above, and the rewritten compression data canbe stored again in the former memory area. However, in case of avariable compression rate, as shown in FIG. 6B, the data quantity of thecompression data is different by the signal characteristics of theimage, which is the object to be compressed, and so informationindicating the data quantity is stored at the time of executing thecompression processing, and a transformation means for the imagelocation and the memory address must be provided. When means for thistransformation is provided, edit processing using the compression datacan be realized without depending on the compression method.

Reproducibility of color is one of the picture quality characteristicsof a color printer. For example, it is desirable for the same color tobe reproduced in the printed result of the display in the same imagedata. But, since the coloring principles of both are different, signaltransformation is indispensable. In case the compression methodseparates the color signals and the resolution of the image data, signalprocessing at high speed can be realized by signal conversion only ofthe compression data relating to the color signal of the former.

And, there is a case in which the reproduction range of the color islimited as apparatus characteristics of the printer. In this case, it isuseless to designate a signal outside the reproduction range of thecolor as a processing object. For example, even if signals outside thereproduction range of the color in the storing means are stored, thereis no effect in the printed result, and part of the capacity of thestoring means is used needlessly. In such a case, it is desirable toadopt a signal system to remove any signal outside the reproductionrange of the color.

FIG. 7A to FIG. 7E show an example of the signal processing of theprinter controller described above. On the basis of the command inputfrom the host computer, characters, graphics and color images aredeveloped, and are converted into compression data by using thecompression means to store them in the code memory. The compression datais restored by using the decompression means and is output as imagedata. Then, combining these means, picture quality processing, such asgamma transformation, color transformation, image area separation, UCR(Under Color Reduction), edge emphasis, etc. is carried out. Further,only part of the object is expanded from the compression data stored inthe code memory, and edit processing, such as overwrite, rotation,expansion and minification, trimming, etc. is also carried out. Thisedit processing is executed on the basis of the command input from thehost computer as mentioned before.

(a) Edit Processing (re-writing of the image data)

In this case, on the basis of a command input from the host computer,image data, such as characters, graphics and a color image, etc. arewritten without considering the image data of the background.

(b) Edit Processing (overwriting on the stored image data)

The image data for the background is overwritten on the image data fromthe host computer. In case the character data is overwritten, forexample, the image data for the background in the range where thecharacters exist is expanded from the memory and the character data iswritten in every bit. The image data edited like this is compressedagain and stored in the memory.

(c) Function Expansion (reduction of the picture quality degradation bymemory duplication)

The capacity of the code memory is not limited. The value of the fixedcompression rate can be set to be able to store the compression data inthe memory on the basis of the memory capacity. Therefore, for the useof a picture quality degradation which is not permissible, thedegradation of the picture quality can be reduced by extending thememory capacity and lowering the compression rate employed in thecompression method.

The above apparatus construction and the signal processing can providefor simplification of the apparatus construction and the signalprocessing in case of a fixed compression rate. However, even when thecompression method uses a variable compression rate, the effect of thememory cutback can be realized by storing the compression data byemploying means for associating the image area with the compression datapositions. There are combinations of signal processing and means otherthan ones shown above. For example, picture quality processing can beprocessed by the host computer in advance, and the signal processing canbe done before edit processing is executed. Based on the basicconstruction of the present invention like that described above, theeffect of the memory cutback can be obtained by storing the compressiondata.

FIG. 8 is a timing chart for outputting a color signal on the basis ofthe coloring principle of a printer engine in accordance with the colororder of the printing means. In case the printing means of the printerengine prints each color in the color-plane order, the signals of oneline for three colors is taken out from the storing means, and it isoutput after picture quality processing of the color transformation,etc. using the signal of the three colors, in order to output thesignals of one color for one line. In order to improve the picturequality of the printing color, the printer sometimes prints using an inkor toner having a specific spectrum in addition to the three elementarycolors. One example is black color (Bk), which is generally called UCR(Under Color Reduction). Since the black color signals are formed fromthe three elementary color signals by signal processing, the threeelementary color signals need to be multiple value signals.

In the example of FIG. 8, when printing four colors (C, M, Y, BK)containing the black color signal, three elementary color signals(R,G,B) stored as compression data are read out from the storing means,and in case where the coding method uses a fixed compression ratewherein signals are output, the data construction of the compressiondata is understood. Only compression data necessary for the colortransformation are designated as the object signals of the colortransformation, and so speed-up of signal processing can be realized.

An example of the more detailed apparatus construction of the printercontroller is shown in FIG. 9, wherein the apparatus is composed of CPU201, memory 204, a signal input/output interface, etc., The exampleshows a construction which can carry out various printer operations. Theability of the printer engine is classified into the categories of blackand white two colors, black and white multiple values, multicolor,full-color, etc. While appropriate constructions of the printercontrollers are conceivable, it is possible to design the constructionof the printer controller such that it can be commonly employed. Thecompression means and the decompression means can be realized byhardware or signal processing of CPU 201, and several fixed compressionrates can be selected on the basis of conditions, such as the picturequality, the resolution and the memory capacity, etc. By this selection,the means for the conditions which are selected by the apparatus itselfcan be provided from the conditions of the apparatus.

(2) A Display Unit

Three examples of the apparatus for displaying a color image,characters, graphs, etc. on a CRT (Cathode Ray Tube), LCD (LiquidCrystal Display), etc. are shown in FIGS. 10A to 10C. In theconventional image displays, the input, format or edited image data arestored in the frame memory in a bit map form, and the data is outputaccording to the scanning order of the display unit. Since the displayunit itself does not have a capability for storing the display data, thesignals are output from the frame memory at the speed of 30 frames persecond, for example.

Problems occur, such as the increase of the memory capacity due to thepicture quality improvement, similar to those of the printer controller.Thus, the image data is stored as compression data, and the compressiondata is decompressed and output step by step according to the scanningorder and the display timing of the display unit so that the neededmemory capacity can be reduced. According to this feature, the framememory of the so-called bit map form memory, that is, a memoryconstruction by which the signals of the amplitude range are assigned toevery display pixel, is no longer necessary.

FIG. 10A shows a construction wherein a two port memory is used asstoring means 103 for the compression data, and the compression data ofthe memory is restored and output using decompression means 104. Theimage data to be displayed is generated by CPU 201, and the data iswritten in memory 103 after converting it into compression data. Thus,the non-compression image data, other than the data output ofdecompression means 104, is not transmitted to the interface forconnecting between the elements. Therefore, the data transmissionability in each interface can be given an allowance.

FIG. 10B shows an example of the apparatus for generating the image datato be displayed by using a display control LSI. CPU 201 conveys thecontents to be shown to the display control LSI as a command so that theLSI forms the image data, and the data is stored in the memory (storingmeans 103) in the form of compression data. Therefore, thenon-compression image data and compressed image data are not transmittedto the interface. Allowance of data transmission ability in theinterface can be further improved as compared with the case of FIG. 10A.

FIG. 10C shows a construction which is effective for CPU 201 of the highsignal processing capacity, wherein CPU 201 generates the image data andstores it in the memory (storing means 103) in the form of compressiondata. The image data to be displayed is decompressed and output. Sincethe data transfer between CPU 201 and memory 103 is performed by thecompression data, the data transmission ability in the interface can begiven an allowance. There are advantages shown in the following when theabove apparatus constructions are used.

(a) An image display with no visual degradation can be realized with asmall memory capacity.

(b) In the case of a signal output to the display unit of highresolution or frame rate, the data transfer rate from the storing meanscan be set low.

(c) The data quantity to be written in the storing means is small.Therefore, the overlap of the term for data writing and the term for thedata output to the display unit can be reduced.

Further, in case the color reproduction, which is one of thecharacteristics of the display unit, is corrected by digital signalprocessing, the correction can be realized by color transformation usingthe compression data. In the case where the three colors of red, greenand blue are represented by signals of 8 bits, for example, when thecolor transformation is realized by a translation table, a memory withoutput data of 24 input address lines and 24 bits is necessary. On theother hand, when the color transformation is obtained by calculation onthe basis of a transformation expression, rather than by use of atranslation table, signal processing corresponding to the translationtable for each pixel is necessary. If the signal processing in the stateof the compression data of the color signal can be performed, the loadimposed by the calculation can be reduced. For example, in case signalsin a block composed of several pixels is represented by two kinds ofcolors and the selection signal showing their difference, thetransformation can be carried out by using compression data representingthe color which is obtained by this procedure. Therefore, there is noneed for decompression of the compression data. Because of a cutback ofthe data quantity as the object of signal processing, advantages such asspeed-up of the processing speed or simplification of the apparatus canbe achieved.

In addition, when the coding method uses a fixed compression rate asmentioned above, the data construction of the compression data becomesclear, and when the input or the formation of the image data is executedin the form of compression data, the data writing into the storing meanscan be executed without carrying out signal processing by thecompression means.

(3) A Filing Apparatus

It is one of the functions required for the filing apparatus to retrievedata at high speed and display the image data which is stored in a largecapacity file and converted into compression data. In order to certainlyand quickly find the desired image data, a retrieval using only akeyword, etc. is not sufficient. It is desirable that the correspondingimage shown in FIG. 11A is approximately displayed. For this purpose,the image data of all image planes are sub-sampled for the purpose ofdisplaying image data of all image planes at minification. When thecorresponding image data is sub-sampled after all the data has beendeveloped, the necessary memory capacity will become huge, and highspeed decompression processing of the compression data and subsamplingprocessing for a large quantity of data become necessary.

Then, the apparatus construction of the present invention shown in FIG.11B can be applied. The image data input from an external large capacityfile is stored in the compression state in the storing means, and thesubsampling of the compression data is carried out, and the data isrestored to the image data and displayed. Since the compression dataconstitution is understood in advance by the coding method using a fixedcompression rate, the subsampling is easily conducted without expanding,and it is also possible to set the ratio of the subsamplingcorresponding to the minified magnification of the display. Severaloutline image planes are displayed simultaneously by displaying onlysimilar color signals taken out from the block, as shown in FIG. 11A, sothat the data can be retrieved and displayed at high speed.

Further, edit processing for the image data stored can be carried outeasily, as was described above. In the case of a fixed compression rate,since the rotation of the image plane and the minification are easy, theedit function, such as reducing the size of the A4 size by putting twopages side by side to output it as an A4 size plane, which is providedwith the copying machine, etc. can be carried out easily.

(4) LSI

In general, means for calculating and processing signals and means forstoring signals are realized as different entities, and both areconnected by data transfer means. As an embodiment, a CPU (CentralProcessing Unit) or specified LSI is used for calculating processing,and a semiconductor memory or optical or storing means, based on anoptical or magnetic principle, is used for signal storing, and electricwiring is used for data transmission.

There are also problems in the constitution of these means stemming fromthe desire for picture quality improvement. That is, there is anincrease of the memory cost and the signal processing time, an increaseof the data transfer time, etc. However, execution of the data transferbetween the means in the form of compression data is effective forsolving these problems.

Next, due to the progress of LSI technology, unification of thecalculation and processing means and the signal storing means wasrealized so that the present invention could be applied to the case of aso-called one chip device. As shown in FIG. 12A, for example, if thememory for storing the image data for one image plane is united with thecalculation and processing means on one chip, the apparatus constitutionof which the image data at the time of processing closed in one chip LSIis realized. The processing object is not limited to a two-dimensionalplane image. There are the same advantages in an animation image havinga time factor, image planes related to multidimensional spaces, etc. asmentioned above. Further, as shown in FIG. 12B, if the compression andthe decompression means are built in the memory chip for the storingmeans, the memory chip can be dealt with as a memory chip of largememory capacity by the rate of the compressibility. For realizing highspeed signal input/output processing, as cache memory is built in.

(5) Game Instrument

In general, the instrument which carries out image formation, editingand display data on the basis of an interactive procedure is called a TVgame instrument, and signal processing is carried out at the same rateof the animation image. Here, the point different from the foregoingexample of the apparatus is that means for the formation and procedureof the image formation is built in. Therefore, for the purpose of thecompression of the image data, the image formation can be carried outbased on the form of the compression data at the step of the formationof the image.

As shown in FIG. 13, the image data can be separated into a background,a middleground, a foreground, characters, etc. on the basis of theelements of the image plane, and the constitutions of compression means102, storing means 103 and decompression means 104 can be set on thebasis of the characteristics which are different, respectively. Forexample, a relatively high compression rate can be set in the case wherea certain degradation of the picture quality in the background ispermitted. While the degradation of picture quality is not permitted fora noticed character, the maximum image plane size can be set small toproduce non-compressed image data. The parallel transfer of thebackground image plane can be carried out by modifying the address forreading out the compression data.

For the data compression of the color image plane, for example, in casethe signals in the block composed of several pixels are represented byselection signals for two kinds of colors and their difference, it iseasy to carry out the image formation in the form of compression data bythis procedure. Several kinds of colors representing the inside of theblock are determined, and the allocation in the block of the set colorsis determined. The size of this block is not always fixed, but can beset at the external form of a body to be displayed. There are advantagesshown in the following.

(a) The color signals should be generated at every block unit.

That is, because it is not necessary to generate the color signals ofeach pixel, the processing speed can be increased.

(b) Because the compression means is not always equipped as anotherelement, the apparatus construction can be simplified.

(c) Because the image data is handled by the compressed format exceptfor the data output to the display means, the transfer speed of data canbe set low. In addition, signal processing of high speed is possiblebecause only rewriting the object of the image can be edited. Two basicconstitutions for realizing these features are shown in FIG. 14A andFIG. 14B. Since the initial value of the compression data, the signalsrepresenting the maximum value, the minimum value, any signal level orany color of the amplitude range of the signals has only to be writtenin the storing means in advance, the data value can be directly writtenin the storing means without operating the compression means.

(6) Converter of the External Input Signal

The signals input from the outside are input through. the transmissionmeans on the basis of some communication protocol or the storing means,etc. on the basis of the optical or magnetic principle as compressiondata or non-compression data. The compressed data can be restored by thedecompression means and converted into compression data by thecorresponding compression means used in the present invention.

When the compression data input from the outside is not restored at onetime, but is restored step by step, the capacity of the means forstoring the restored signals can be made small. Further, when thesignals input from the outside are the image data, a means for judgingthe input order, etc. of the pixels and the kind of colors thatconstitute the data in advance is provided. For example, the followingjudgments are made.

(a) The header information added to the head of the data is judged.

(b) The specific marker cord (showing the paragraph of the plane) forthe compression data of the variable compression rate is retrieved andthe face of the color image is divided.

(7) Program Compression Equipment

In the explanation of the above example, the same effects can beobtained by applying the present invention to ripple data such as audio,character codes, etc., without limiting the image data of the signals.

For example, in the apparatus construction using a processor forexecuting the calculation, data transfer, etc. based on a program, whenthe program is stored as compression data and when the decompressionprocessing is executed in the processor core, the following areachieved.

(a) The capacity of the program storing memory is reduced.

(b) The data transfer quantity between the processor and the programstoring memory can be reduced.

An example of the apparatus is shown in FIG. 15A. Because it isimpossible to directly refer to the absolute address of the program incase of a variable compression rate, the following measures are needed.

(a) The data is decompressed in advance in the cache memory, etc.

(b) Means for adding indexes to refer to the absolute address for everyprogram step becomes necessary.

An example of the procedure for signal processing by the apparatus ofFIG. 15A is shown in FIG. 15B.

(8) Multiple Media Apparatus

The present invention can be applied to constitute an apparatus forinputting, storing, forming, editing and storing several signals ofdifferent characteristics. The present invention is applied to signalshaving correlativity in the time base direction, such as audio signals,animation images, etc., as shown in FIG. 16. Since compression means 102can compress signals by using signal correlativity in the time basedirection, the effective compression can be carried out by referring topast signals. Then, only signals to be referred to for compressionprocessing are restored and can be used by edit means 105, if the pastdata to be referred to is stored in storing means 103 as compressiondata. Similar to the above, when the compression data is decompressed bydecompression means 104, the past signals also can be referred to.

(9) Compression means of the color image

An example of the compression method of the means for compressing thecolor image is shown in FIG. 17. Colors generated in the blocks (colordecided by combination of the three elementary color signals) arelimited to about two colors and are approximated as one block of severaladjacent pixels from the image data. Then, the selected result of thelimited color is created about each pixel in the block. Therefore, ifthree colors (for example, RGB; red, green and blue) are eachrepresented by an 8 bit signal for 16 pixels of the block size, 384 bitsare necessary for the original data. When approximating the colors totwo colors, the data can be compressed to 64 bits which is ⅙. In thisway, the visual degradation. of the picture quality is hardly recognizedby limiting the kinds of colors generated in the small areas.

The compression rate achieved by this means does not depend on thecharacteristics of the image data of the signals. The compression datacan be differentiated to the signals representing the kinds of thecolors and the signal representing the selection result of the color ofeach pixel. Therefore, in order to transform colors, it is enough to usesignal-processing of the compression data of the former, and to usesignal-processing such as the minification of the rotation andexpansion, etc. for the latter. In order to rewrite a part of the imagedata, only compression data corresponding to the place in the image needbe rewritten.

The block size can be made adjustable, and the value of the fixedcompression rate changes in accordance with the set size. Therefore, onthe basis of the storing capacity (memory capacity) of the storingmeans, the block size is set to set the compression rate so as to beable to store the compression data in the memory.

As mentioned above, the signal processing equipment of the presentinvention reduces the capacity of the memory for storing the image data,and the data transfer rate among means is increased. Further, theformation and the editing of the image data can be executed at highspeed. The present invention is suitable for signal processing equipmentwhich operates to print and display an image.

What is claimed is:
 1. A signal processing equipment, comprising:compression means for converting an input signal into compressed databeing compressed at a fixed compression rate, wherein said compressionmeans comprises: means for dividing said input signal of a color image,where plural pixels are represented by plural color signals, into aplurality of blocks each being composed of a predetermined number ofpixels, means for calculating approximated color signals based on saidplural color signals in said block, and means for selecting anapproximated color signal corresponding to a color signal of each pixelin said block and outputting selected approximated color signals foreach block as said compressed data; a memory which stores saidcompressed data; a processor which reads stored compressed data fromsaid memory; and decompression means for decompressing said compresseddata from said processor, wherein said processor reads compressed datafrom said memory and causes said decompression means to decompress saidcompressed data from said processor in synchronism with a timing ofoutputting decompressed data from said decompression means to an outputdevice, and wherein said processor reads said compressed data from saidmemory, rewrites a part of said compressed data, and stores therewritten compressed data to said memory.
 2. The signal processingequipment according claim 1, wherein said fixed compression rate can beset according to capacity of said memory.
 3. A signal processingequipment, comprising: compression means for converting an input signalinto compressed data being compressed at a fixed compression rate,wherein said compression means comprises: means for dividing said inputsignal of a color image, where plural pixels are represented by pluralcolor signals, into a plurality of blocks each being composed of apredetermined number of pixels, means for calculating approximated colorsignals based on said plural color signals in said block, and means forselecting an approximated color signal corresponding to a color signalof each pixel in said block and outputting selected approximated colorsignals for each block as said compressed data; a memory for storingcompressed data; a display which displays decompressed data; a processorwhich reads compressed data from said memory; and decompression meansfor decompressing said compressed data from said processor, wherein saidprocessor reads said compressed data from said memory, causes saiddecompression means to decompress compressed data from said processor insynchronism with a scanning order and a display timing of said displayand to output decompressed data to said display according to saiddisplay timing of said display, and wherein said processor reads saidcompressed data from said memory, rewrites a part of said compresseddata, and stores the rewritten compressed data to said memory.
 4. Asignal processing equipment, comprising: storing means for storingcompressed data, wherein said compressed data is generated according tothe steps of: dividing an input signal to a plurality of blocks eachbeing composed of a predetermined number of pixels, and said inputsignal being composed of a plurality of pixels having a plurality ofcolor signals, calculating approximated color signals based on saidplurality of color signals in said block, approximating said pluralityof color signals in said block to said calculated approximated colorsignals, selecting said approximated color signals corresponding to acolor signal of each pixels in said block, and converting saidcompressed data into said calculated approximated color signals and saidselected result of said approximated color signals; and decompressionmeans for converting a decompressed data into said compressed data,wherein said decompression means reads said compressed data from saidstoring means and converts said compressed data into decompressed datain synchronism with a timing of outputting said decompressed data fromsaid decompression means to an output device, and wherein said processorreads said compressed data from said memory, rewrites a part of saidcompressed data, and stores the rewritten compressed data to saidmemory.
 5. A signal processing equipment, comprising: compression meansfor converting an input signal into compressed data being compressed ata fixed compression rate, wherein said compression means comprises:means for dividing said input signal to a color image, where pluralpixels are represented by plural color signals, into a plurality ofblocks each being composed of a predetermined number of pixels, meansfor calculating approximated color signals based on said plural colorsignals in said block, and means for selecting said approximated colorsignals corresponding to a color signal of each pixel in said block andoutputting selected approximated color signals for each block as saidcompressed data; a memory which stores said compressed data; a processorwhich reads stored compressed data from said memory; and decompressionmeans for decompressing said compressed data from said processor,wherein said processor reads compressed data from said memory and causessaid decompression means to decompress said compressed data from saidprocessor in synchronism with a timing of outputting decompressed datafrom said decompression means to an output device, and wherein saidprocessor reads out compressed data for rewriting from said memory,calculates an addressing said memory to which rewritten compressed datais to be stored, rewrites said compressed data, and stores the rewrittencompressed data into said memory at the calculated address.
 6. A signalprocessing equipment, comprising: compression means for converting aninput signal into compressed data being compressed data fixedcompression rate, wherein said compression means comprises: means fordividing said input signal to a color image, where plural pixels arerepresented by plural color signals, into a plurality of blocks eachbeing composed of a predetermined number of pixels, means forcalculating approximated color signals based on said plural colorsignals in said block, and means for selecting an approximated colorsignals corresponding to a color signal of each pixel in said block andoutputting selected approximated color signals for each block as saidcompressed data; a memory which stores said compressed data; a displaywhich displays decompressed data; a processor which reads storedcompressed data from said memory; and decompression :means fordecompressing said compressed data from said processor, wherein saidprocessor reads said compressed data from said memory, causes saiddecompression means to decompress said compressed data from saidprocessor in synchronism with a scanning order and a display timing ofsaid display and to output decompressed data to said display accordingto said display timing of said display, and wherein said processor readsout compressed data for rewriting from said memory, calculates anaddress in said memory to which rewritten compressed data is to bestored, rewrites said compressed data, and stores the rewrittencompressed data into said memory at the calculated address.
 7. A signalprocessing equipment, comprising: storing means for storing compresseddata, wherein said compressed data is generated according to the stepsof: dividing an input signal to a plurality of blocks each beingcomposed of a predetermined number of pixels, and said input signalbeing composed of a plurality of pixels having a plurality of colorsignals, calculating approximated color signals based on said pluralityof color signals in said block, approximating said plurality of colorsignals in said block to said calculated approximated color signals,selecting said approximated color signals corresponding to a colorsignal of each pixel in said block, and converting said compressed datainto said calculated approximated color signals and said selected resultof said approximated color signals; and decompression. means forconverting a decompressed data into said compressed data, wherein saiddecompression means read said compressed data from said storing meansand converts said compressed data into decompressed data in synchronismwith a timing of outputting said decompressed data from saiddecompression means to an output device, and wherein said processorreads out compressed data for rewriting from said memory, calculates anaddress in said memory to which rewritten compressed data is to bestored, rewrites said compressed data, and stores the rewrittencompressed data into said memory at the calculated address.